Recent advances in radiosensitivity determinants in melanoma

Synthetic selenomelanin nanoparticles radio-sensitize non-melanocytic lung cancer (A549) cells by promoting G2/M arrest

Recent studies have postulated the natural existence of selenomelanin and its role in the radio-protection of healthy cells. The present study aimed to understand its radio-modulatory activity in non-melanocytic cancerous (A549) cells of lung origin. Briefly, selenomelanin was synthesized under laboratory conditions following the previously reported methodology. The various spectroscopic (electron paramagnetic resonance, X-ray photoelectron spectroscopy, atomic absorption spectroscopy, transmission electron microscopy and dynamic light scattering) analyses confirmed the formation of selenomelanin nanoparticles. The short-term (72 h) and long-term (14 days) toxicity profiling of selenomelanin by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) and clonogenic assays respectively revealed its half maximal inhibitory concentrations (IC50) of 72.03 ± 7.13 μg/ml and 0.85 ± 0.16 μg/ml respectively in A549 cells and of 81.56 ± 1.63 μg/ml and > 5 μg/ml respectively in healthy lung fibroblast (WI26) cells. Further, pre-treatment of selenomelanin (at concentrations non-toxic for WI26 cells) selectively augmented the radiosensitivity of A549 cells. Finally, mechanistic investigations in A549 cells revealed that selenomelanin increased the levels of reactive oxygen species, DNA damage and modulated the phospho-levels of CHK1 and CHK2 (effectors of cell cycle arrest) in the irradiated cells to favour G2/M arrest followed by cleavage of caspase 3 (effector of apoptosis). Together, the present study proposes the novel application of selenomelanin as a radiosensitizer to enhance the efficacy of radiotherapy in cancerous cells of lung origin.

Genomic Profiling Reveals SMARCA4 Mutations Are Associated with Shorter Overall and Intracranial Progression-Free Survival in Patients with Melanoma Brain Metastases

PURPOSE

Melanoma brain metastases (MBM) are a common and lethal complication of metastatic melanoma. Despite improvements in treatments, subsets of patients with MBM experience rapid clinical decline, and currently, few prognostic biomarkers have been identified. An improved understanding of the molecular features specifically associated with MBM overall survival (OS) and intracranial progression-free survival (PFS) could facilitate the development of more effective clinical management strategies.

EXPERIMENTAL DESIGN

We established an initial cohort of 102 MBMs, 970 unmatched melanoma extracranial metastases (ECM), and 569 unmatched melanoma primaries with available targeted exome sequencing data covering 182 genes and a validation cohort of 50 MBMs with SMARCA4 genomically profiled. Kaplan-Meier analysis, log-rank test, and Cox proportional hazards model were used to evaluate associations between pathogenic genomic alterations and OS and intracranial PFS. We evaluated 14 MBMs and 19 ECMs with paired RNA sequencing and whole-exome sequencing data to identify genotype-transcriptome correlations.

RESULTS

Of 43 genes significantly mutated among MBMs, only pathogenic mutations in SMARCA4 significantly associated with shorter OS and intracranial PFS on univariable and multivariable analyses in patients with MBM but not from first ECM or primary tumor diagnosis. SMARCA4 mutations significantly associated with enrichment of oxidative phosphorylation and depletion of immune signaling gene sets.

CONCLUSIONS

Pathogenic SMARCA4 mutations independently predict an association with shorter OS and intracranial PFS in patients with MBM and associate with expression of pathways known to mediate melanoma virulence. These findings add to our understanding of MBM pathogenesis and suggest their potential use as prognostic biomarkers in patients with MBM and possible therapeutic opportunities.

Oxidative State in Cutaneous Melanoma Progression: A Question of Balance

Reactive oxygen species (ROS) are highly bioactive molecules involved not only in tissue physiology but also in the development of different human conditions, including premature aging, cardiovascular pathologies, neurological and neurodegenerative disorders, inflammatory diseases, and cancer. Among the different human tumors, cutaneous melanoma, the most aggressive and lethal form of skin cancer, is undoubtedly one of the most well-known "ROS-driven tumor", of which one of the main causes is represented by ultraviolet (UV) rays' exposure. Although the role of excessive ROS production in melanoma development in pro-tumorigenic cell fate is now well established, little is known about its contribution to the progression of the melanoma metastatic process. Increasing evidence suggests a dual role of ROS in melanoma progression: excessive ROS production may enhance cellular growth and promote therapeutic resistance, but at the same time, it can also have cytotoxic effects on cancer cells, inducing their apoptosis. In this context, the aim of the present work was to focus on the relationship between cell redox state and the signaling pathways directly involved in the metastatic processes. In addition, oxidative or antioxidant therapeutic strategies for metastatic melanoma were also reviewed and discussed.

Anandamide-Modulated Changes in Metabolism, Glycosylation Profile and Migration of Metastatic Melanoma Cells

Simple Summary

Anandamide (AEA) belongs to the group of endocannabinoids and possesses various regulatory properties in physiological as well as pathological processes occurring in the organism. In this research some basic biological tests were applied to investigate AEA-induced changes in cell metabolism and motility, as well as advanced biophysical methods for the determination of the differences in the cell glycosylation profile on a highly dangerous model of melanoma skin cancer, for which an effective therapy is not yet available. Our research suggests that anandamide treatment of metastatic melanoma cells increases the cell metabolism which leads to the reduction in the metastatic potential of cells in terms of the cell glycosylation profile and cell migration. In the view of our research, it can be presumed that anandamide usage in the combined therapy of advanced melanoma would be an advantage for the patient.

Abstract

An effective therapy for advanced melanoma, a skin cancer with the highest mortality, has not yet been developed. The endocannabinoid system is considered to be an attractive target for cancer treatment. The use of endocannabinoids, such as anandamide (AEA), is considered to be much greater than as a palliative agent. Thus, we checked its influence on various signaling pathways in melanoma cells. Our investigation was performed on four commercial cell lines derived from different progression stages (radial WM35 and vertical WM115 growth phases, lymph node WM266-4 metastasis, solid tumor A375-P metastasis). Cell viability, glucose uptake, quantification of reactive oxygen species production, expression of selected genes encoding glycosyltransferases, quantification of glycoproteins production and changes in the glycosylation profile and migration, as well as in cell elastic properties were analyzed. The cell glycosylation profile was investigated using the biophysical profiling method—the quartz crystal microbalance with dissipation monitoring (QCM-D). Anandamide treatment of only metastatic cells resulted in: an increase in the cell metabolism, a decrease in GFAT-1 and DPM1 expression, followed by a decrease in L1-CAM glycoprotein production, which further influenced the reduction in the cell glycosylation profile and migration. Considering our results, AEA usage is highly recommended in the combined therapy of advanced melanoma.